While some automakers are in favor of renewable fuels, one group in particular is in no rush to bring E15 to the market.

According to a new report from The Detroit News, the Alliance of Automobile Manufacturers -- which consists of Detroit’s Big Three, Volkswagen AG, Toyota Motor Corp. and others -- feels that E15 could turn out to be troublesome for vehicles if proper testing isn't conducted first.

"It is not in the long-term interest of the government, automakers, fuel providers or the ethanol industry itself to find out down the road that vehicle problems are occurring from rushing E15 into the national marketplace," said Gloria Bergquist, a spokeswoman for the Alliance of Automobile Manufacturers.

"EPA approved an E15 waiver before sufficient testing was completed to gauge the cumulative effects of this more corrosive fuel. Ethanol can permeate and degrade rubber, plastic, metal and other materials in vehicles not designed to handle it.”

E15 is a renewable fuel blend of 15 percent ethanol and 85 percent gasoline. The U.S. Environmental Protection Agency (EPA) approved the use of E15 for 2001 model year vehicles and newer, and automakers like Volkswagen AG, GM and Ford have even approved it for some of their latest models.

But worries remain about whether the EPA is pushing E15 onto the market too quickly without proper testing of its effects on vehicles first. Automakers like Chrysler still haven't approved the fuel, and even say its use could void warranties.

Almost all of the U.S.' gas pumps offer E10, which is a blend of 10 percent ethanol and 90 percent gasoline. Some automakers argue that the added ethanol in E15 could be more taxing on vehicles than the E10.

This isn't the first time automakers have spoke out against E15. Last year, a study backed by American Fuel & Petrochemical Manufacturers found that the E15 formula damaged engines in two of the eight vehicles used in high mileage tests. The cars in the study were EPA-approved to run on E15.

E15 in particular has been a hot topic this year. In August, the EPA froze a planned bump in ethanol levels that was set for next year. The freeze came after state efforts to ban E15, and House debates on whether to cut the blending requirements entirely.

In 2012, only 4.55 billion bushels of corn was used to produce ethanol, which was down from 5 billion bushels in 2011. About 13.33 billion gallons of ethanol was produced last year, missing the goal of 15.2 billion gallons.

Ethanol opponents say the use of ethanol blends takes away from the nation's corn crops, and livestock farmers saw the cost of feed inflated by having to compete with ethanol. In addition, environmentalists say corn ethanol produces more emissions over its life cycle than oil.

In September of this year, the Renewable Fuels Association (RFA) said American consumers are paying between 50 cents and $1.50 per gallon less for gasoline due to the addition of ethanol blends. The analysis further said that consumers are saving from $700 billion to about $2.6 trillion annually on gas because of ethanol, and that oil prices would be $15 to $40 a barrel higher than they are today without ethanol added in.